Surface functionalization of inorganic nanoparticles with DNA, RNA, peptides and dyes is needed for the assembly of nanoscale materials for a variety of applications ranging from biosensing, to bioimaging, and therapeutics. A critical step in building these hybrid biomaterials is the ability to present diverse chemical functionalities at a nanoparticles surface efficiently and in high enough yields to assemble diverse ligands. Chemical bioconjugation strategies, including the more common EDC approach for amide coupling and the use of thiol reactive linkers have been predominantly used for attaching peptides, dyes and nucleic acids to nanoparticles (NPs). This is attributed to their compatibility with aqueous conditions and their tolerance for higher salt concentrations that biomolecules often require to maintain their folded structures. However, such chemical conjugation strategies often require the pairing of a different chemical modification for each individual substrate to be attached to a NPs surface depending on the reactive sites available for functionalization.
In light of this multistep synthetic approach to nanoparticle functionalization, a generalized chemical approach was developed that is both biologically compatible and straightforward. A DNA functionalized NP (DNA-NP) was used as a platform on which to test the enzyme-mediated approach to nanoparticle functionalization. DNA-NPs have gained significant attention in the last two decades, owning to their ease of synthesis and chemical stability in aqueous environments. Hybridization-based assembly of nanomaterials takes advantage of the Watson-crick base pairing interactions of DNA's double helical structure.
To date there is no general enzymatic strategy for modification of the DNA on a DNA-nanoparticle to impart compatibility for chemical ligation between the DNA and a molecule of non-nucleic acid structure. The methods and compositions disclosed herein use the terminal ends of DNA molecules, in particular, the 3′OH end recognized by ligase enzymes. Disclosed herein are compositions that can interface chemical modifications with the specificity of the ligase. This versatile approach is important for the rapidly growing field of nucleic acid based therapeutics and offers an important strategy aimed at repurposing enzymes for use as assembly tools for functionalizing nanomaterials in a chemically specific manner.